If that will dribble down to us end users in Mint, that can be a good thing.

I won't "upgrade" to a new version until the one I have is no longer supported,
and then that means that the "new version" is almost end of life already... and I am having to learn new tweaks to make it "my style".

Important to note Canonical supports only the main and (working with vendors, as it's closed source) restricted repositories. Commonly, as on Linux Mint, people also enable the community supported universe and multiverse repositories. I don't imagine those will be supported for 10 years. Those are barely supported for 5 years as is (some packages get good support for entire 5 years, others cap off earlier or don't get any support).

So for home servers, where the main repository likely suffices, I'd be happy to run 10 years. For other home use? Not so much.

Important to note Canonical supports only the main and (working with vendors, as it's closed source) restricted repositories. Commonly, as on Linux Mint, people also enable the community supported universe and multiverse repositories. I don't imagine those will be supported for 10 years. Those are barely supported for 5 years as is (some packages get good support for entire 5 years, others cap off earlier or don't get any support).

So for home servers, where the main repository likely suffices, I'd be happy to run 10 years. For other home use? Not so much.

Currently universe and multiverse only get paid support from Canonical

They do? I looked at Ubuntu Advantage but can't find details that suggest they do updates for universe and multiverse. If they have a repository with package updates for universe accessible only to paying users, they'd still have to publish the source code of GPL licensed packages. I'd imagine a smart community maintainer would then just repackage that and put it back in universe (like CentOS does with RHEL packages).

Currently universe and multiverse only get paid support from Canonical

They do? I looked at Ubuntu Advantage but can't find details that suggest they do updates for universe and multiverse. If they have a repository with package updates for universe accessible only to paying users, they'd still have to publish the source code of GPL licensed packages. I'd imagine a smart community maintainer would then just repackage that and put it back in universe (like CentOS does with RHEL packages).

They do, at least so their site says:

ubuntu.com wrote:Customers of Canonical often ask for an extended security maintenance commitment, either to ‘main’ for a longer period of time, or to ‘universe’ software packages during the initial maintenance period of the LTS. This is known as 'Extended Security Maintenance' or ESM and is available for LTS releases since Ubuntu 12.04 LTS.

I don't know about the smart community maintainers. If they were so willing to update it then I'd imagine they'd do that based on upstream already, but dunno. I'm more surprised that kernel live patching remains relatively exclusive to the paid packages. I mean you can do it manually but nobody "lifted" the paid packages for all I know (different license but when did that ever stop anybody?!).

Canonical’s Ubuntu Security Team are committed to providing fixes for HIGH and CRITICAL CVEs against the most commonly used server packages in the Ubuntu Main archive. This is essentially a continuation of the same security updates that Ubuntu 12.04 Server users have always received.

Similarly in ESM — what’s covered? it list specifically which packages are maintained and those are all from main. It also says:

During the Extended Security Maintenance phase of the Ubuntu 12.04 LTS release, Canonical will provide security maintenance to a wide range of binary packages that are commonly used in cloud and server workloads. Extended Security Maintenance is included for 64-bit x86 AMD/Intel installations.

The services apply only to packages found in the Ubuntu Main Repository and Canonical-owned packages in the Universe Repository except (i) the "proposed" and "backports" repository pockets, and (ii) the exclusions noted in the applicable support scope documentation.
The supported packages from the Universe Repository include, but may not be limited to, Juju packages, MAAS packages, the nova-conductor package, and their dependencies to the extent used in connection with those packages.

You're likely right in that those additional 5 years support will be similar to above existing extended support. Either paid or not, it will undoubtedly also focus on server packages.

And minimum order is 50 support contracts (at $ 150 a year) for desktop ESM (pricing). So can be of interest to medium sized companies but smaller companies and home users don't quality for desktop ESM.

In short, the news probably only makes a difference for people running commercial servers. For everybody else nothing changes.

...at least at first thought, the following comes to mind:
python2 goes eol in 2020. Just how easy it is to continue supporting such until 2028?
Edit: maybe they don't - as it's not part of the default install - only python3 instead?
Secondly, systemd. Red Hat can 'promise' as many yrs of support they want to, simply because they were / are in direct control of such.
Then again you'll tell me, the older RHEL 6 used / uses...Upstart, and will continue getting extended support until 2024 from what i read...
Quite a big leap for Canonical all in all.

.
For free or non-commercial Ubuntu 18.04 and LM 19 users, LTS support will likely remain unchanged at 5 years, ie not extended to 10 years.

AFAIK, companies can run Ubuntu Server 18.04 LTS for free for 5 years only. Longer than that, they have to pay annual subscriptions to Canonical Inc for extended support, called Ubuntu Advantage.
....... Maybe, Ubuntu Advantage, previously, could only be extended for a maximum 3 years. With Mark Shuttleworth's announcement, Ubuntu Advantage can now be extended to 5 years max = free 5 + paid 5 = 10 years. Or maybe, he meant 5 + 10 years max of paid extended support for Ubuntu Server 18.04 LTS = total support of 15 years.

In comparison, each non-free or commercial RHEL version is supported for 10 years but companies have to pay annual subscriptions to Red Hat Inc from Year-1 until Year-10, in order to receive security updates and other support(= mainstream/features-added and extended) = maximum 10 years of paid support = SaaS.

Hence, the 2017 revenue for Canonical Inc is only about US$126 million while for Red Hat Inc is about US$2 billion.
.

P S - Red Hat Inc's free CentOS, based on RHEL, is also supported for 10 years for each version but users must upgrade yearly in order to remain supported, eg from CentOS 7.0 to 7.1 to 7.2 to 7.3 to 7.4 to 7.5 and so on = like running Win 10 Pro. Similarly for Red Hat's free Fedora, ie must upgrade at least yearly.

I don't see anything in Shuttleworth's comment about only paid support for 10 years. It says Ubuntu 18.04 LTS will get 10 years support. That is likely only security updates, but seems clear to me.
Also, mimicking Redhat--which is likely why Shuttleworth is doing this--CentOS gets the same support time as regular Redhat.

My hunch was correct, ie Canonical Inc only provided extended support for Ubuntu 12.04 LTS for a maximum of 3 years, ie from its EOL in April 2017 until April 2020. ... https://www.ubuntu.com/esm . Similarly for Ubuntu 14.04/16.04 LTS, ie free 5 years + paid 3 years = total maximum of 8 years of LTS support.

So, Mark Shuttleworth's announcement of 10 years of Ubuntu 18.04 LTS support means companies can now use Ubuntu 18.04 LTS for free for up to 5 years until its EOL in April 2023 and then may have to pay for extended support under Ubuntu Advantage for a maximum of another 5 years until April 2028 = free for 5 years + paid extended support for another 5 years max = max of 10 years of LTS support.

In comparison, for Ubuntu 16.04 LTS, extended support is only for a max of 3 years after its EOL in April 2021, ie will end in April 2024.

My hunch was correct, ie Canonical Inc only provided extended support for Ubuntu 12.04 LTS for a maximum of 3 years, ie from its EOL in April 2017 until April 2020. ... https://www.ubuntu.com/esm . Similarly for Ubuntu 14.04/16.04 LTS, ie free 5 years + paid 3 years = total maximum of 8 years of LTS support.

So, Mark Shuttleworth's announcement of 10 years of Ubuntu 18.04 LTS support means companies can now use Ubuntu 18.04 LTS for free for up to 5 years until its EOL in April 2023 and then may have to pay for extended support under Ubuntu Advantage for a maximum of another 5 years until April 2028 = free for 5 years + paid extended support for another 5 years max = max of 10 years of LTS support.

In comparison, for Ubuntu 16.04 LTS, extended support is only for a max of 3 years after its EOL in April 2021, ie will end in April 2024.

Where is your source for this? Where does Shuttleworth say 10 years Ubuntu 18.04 support Including 5 paid years?